We used to play that kind of format in the past, we called it PentaColor in italy, 5 mages with one different color each and no more than 2 o 3 artifacts (appropriate mox and sol ring usually)...

after some months it turned out it was better to play it without a defined ally/enemy policy but everyone against everyone, and it was nice because for the first half of the game it looked more like a role play where people were trying to find allies and turn other mages against the most feared opponent.

Games were quite long, a single pentacolor game was lasting usually more than one hour i remember...
it was more than 20 years ago...

@Teluin Was pondering. Could always just cut Efreet? It's just so flavorful to me to have the green Djinn AND the green Efreet. Maybe 2xBoP and 2x Llanowar elves? Or would you cut something else like Archers for more acceleration?

@BandsWithOthers I agree Djinn and Efreet are awesome. I think it depends what the deck wants to do - Mono G's strength is in ramp, right? I think BoP being in the air is relevant. Since it's vs. other mono coloured decks, how and when Efreet is used is determined by its owner, so you can ensure it is used to your advantage. I'd probably cut Druid and add Birds and Avoid Fate. With the mana you could consider a Tome as well to give some non-Sylvan card advantage. Btw Regrowth and Archers rock :)

@Teluin Regrowth is a pretty sweet effect but I wasn't sure how much this deck would need recursion. In some ways it's hard shutting off the regular vintage brain! I Can dig cutting Druid, Having trouble deciding. Let's see what happens cutting a fog.

@Thewhitedragon69 In this format winning requires killing both opponents, assuming your "allies" don't interfere to keep you from winning. I Enjoy Hordes, and I was also considering Lord of the Pit, but this deck doesn't put up enough creatures. I figured Juzam would be plenty of beef without making the deck too hyper agressive in this closed format. Also, the only P9 in these lists is Timetwister, just because it's a fun blue bomb in a multiplayer.

So red should totally have Mana Flare. Also Inferno is clutch fun too. Just trying to think of cards that were amazing in multiplayer back in highschool. Gaeas Leige plus instill energy was game ending many times. Also Oubilett (spelling?) and Paralyze are both great cards for black.